Vital signs sensor and method of measuring vital signs of a user

Abstract

PPG sensor emits light at at least three wavelengths (Y 1 -Y 3 ) and detects the reflected light. The PPG sensor comprises a motion correction unit ( 130 ) for correcting motion artefacts from the detected light signals by subtracting the output signal of the detected light at the second wavelength (Y 2 ) from an average of an output signal of the detected light at the first and third wavelength (Y 1 , Y 3 ). The three wavelengths (Y 1 -Y 3 ) are arranged around 550 nm. The second wavelength (Y 2 ) is arranged equal distantly between the first and third wavelength.

The invention claimed is: 
     
       1. An optical vital signs sensor configured to measure vital signs of a user, the optical vital signs sensor comprising:
 a light source configured to generate light at at least three wavelengths (Y 1 −Y 3 ) which is directed towards a skin of the user, wherein the first, second and third wavelengths (Y 1 −Y 3 ) are arranged approximately around 550 nm, wherein the second wavelength (Y 2 ) is arranged equidistantly between the first wavelength and third wavelength (Y 1 ,Y 3 ), 
 a photo detector configured to detect an intensity of light at the at least three wavelengths, wherein said light is indicative of a reflection of light emitted in or from the skin of the user, and 
 a computer that performs motion correction to correct motion artifacts from the light intensity detected by the photo detector, wherein performing the motion correction includes subtracting the light intensity detected at the second wavelength from an average of the light intensity detected at the first wavelength (Y 1 ) and that at the third wavelength (Y 3 ). 
 
     
     
       2. The optical vital signs sensor according to  claim 1 , wherein the second wavelength (Y 2 ) corresponds to approximately 550 nm, the first wavelength (Y 1 ) corresponds to approximately 530 nm, and the second wavelength (Y 2 ) corresponds to approximately 570 nm. 
     
     
       3. The optical vital signs sensor according to  claim 1 , wherein said optical vital signs sensor is a photoplethysmographic sensor. 
     
     
       4. The optical vital signs sensor according to  claim 1 , wherein the second wavelength (Y 2 ) corresponds to approximately 550 nm, the first wavelength (Y 1 ) corresponds to approximately 540 nm, and the second wavelength (Y 2 ) corresponds to approximately 560 nm. 
     
     
       5. The optical vital signs sensor according to  claim 1 , wherein the computer further determines a vital sign of the user, at least based on correcting the motion artifacts from the light intensity detected by the photo detector. 
     
     
       6. The optical vital signs sensor according to  claim 5 , wherein the vital sign of the user includes heart rate. 
     
     
       7. The optical vital signs sensor according to  claim 1 , wherein the light sources includes one or more optical fibers and the light is provided via the one or more optical fibers. 
     
     
       8. A method of measuring vital signs of a user with an optical vital signs sensor, the method comprising operations that include:
 generating light at at least three wavelengths (Y 1 −Y 3 ) which are directed towards a skin of the user; 
 detecting an intensity of light at the at least three wavelengths (Y 1 −Y 3 ), wherein said light is indicative of a reflection of light emitted from the skin of the user; and 
 correcting motion artifacts from the detected light by subtracting the light intensity detected at the second wavelength (Y 2 ) from an average of the light intensity detected at the first wavelength (Y 1 ), and at the third wavelength (Y 3 ),
 wherein the first, second and third wavelengths (Y 1 −Y 3 ) are arranged approximately around 550 nm, and wherein the second wavelength (Y 2 ) is arranged equidistantly between the first and third wavelength (Y 1 ,Y 3 ). 
 
 
     
     
       9. The method according to  claim 8 , wherein the second wavelength (Y 2 ) corresponds to approximately 550 nm, the first wavelength (Y 1 ) corresponds to approximately 530 nm, and the second wavelength (Y 2 ) corresponds to approximately 570 nm. 
     
     
       10. The method according to  claim 8 , wherein the second wavelength (Y 2 ) corresponds to approximately 550 nm, the first wavelength (Y 1 ) corresponds to approximately 540 nm, and the second wavelength (Y 2 ) corresponds to approximately 560 nm. 
     
     
       11. The method according to  claim 8 , wherein said optical vital signs sensor is a photoplethysmographic sensor. 
     
     
       12. The method according to  claim 8 , further comprising:
 determining a vital sign of the user, at least based on correcting the motion artifacts from the detected light. 
 
     
     
       13. The method according to  claim 12 , wherein the vital sign of the user includes heart rate. 
     
     
       14. The method according to  claim 8 , wherein the light is provided via one or more optical fibers of the optical vital signs sensor. 
     
     
       15. A non-transitory computer readable storage medium that stores a computer program that, when executed at a computer that is controlling an optical vital signs sensor, causes performance of operations that include:
 generating, via the optical vital signs sensor, light at at least three wavelengths (Y 1 −Y 3 ) which are directed towards a skin of the user; 
 detecting, via the optical vital signs sensor, an intensity of light at the at least three wavelengths (Y 1 −Y 3 ), wherein said light is indicative of a reflection of light emitted from the skin of the user; and 
 correcting, via the computer, motion artifacts from the detected light by subtracting the light intensity detected at the second wavelength (Y 2 ) from an average of the light intensity detected at the first wavelength (Y 1 ), and at the third wavelength (Y 3 ),
 wherein the first, second and third wavelengths (Y 1 −Y 3 ) are arranged approximately around 550 nm, and wherein the second wavelength (Y 2 ) is arranged equidistantly between the first and third wavelength (Y 1 ,Y 3 ). 
 
 
     
     
       16. The non-transitory computer readable storage medium according to  claim 15 , wherein the second wavelength (Y 2 ) corresponds to approximately 550 nm, the first wavelength (Y 1 ) corresponds to approximately 530 nm, and the second wavelength (Y 2 ) corresponds to approximately 570 nm. 
     
     
       17. The non-transitory computer readable storage medium according to  claim 15 , wherein the second wavelength (Y 2 ) corresponds to approximately 550 nm, the first wavelength (Y 1 ) corresponds to approximately 540 nm, and the second wavelength (Y 2 ) corresponds to approximately 560 nm. 
     
     
       18. The non-transitory computer readable storage medium according to  claim 15 , wherein said optical vital signs sensor is a photoplethysmographic sensor. 
     
     
       19. The non-transitory computer readable storage medium according to  claim 15 , wherein the operations further include:
 determining a vital sign of the user, at least based on correcting the motion artifacts from the detected light. 
 
     
     
       20. The non-transitory computer readable storage medium according to  claim 19 , wherein the vital sign of the user includes heart rate.